MCP48CMB21 datasheet(75/106 Pages) MICROCHIP

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DS20006160A-page 75

MCP48CXBXX

8.0

TYPICAL APPLICATIONS

The MCP48CXBXX devices are general purpose,

single/dual-channel voltage output DACs for various

applications where a precision operation with low power is

needed.

Applications generally suited for the devices are:

• Set Point or Offset Trimming

• Sensor Calibration

• Portable Instrumentation (Battery-Powered)

• Motor Control

8.1

Design Considerations

In the design of a system with the MCP48CXBXX

devices, the following considerations should be taken

into account:

• Power Supply Considerations

• Layout Considerations

8.1.1

POWER SUPPLY

CONSIDERATIONS

The power source supplying these devices must be as

clean as possible. If the application circuit has separate

digital and analog power supplies, VDD and VSS may

reside on the analog plane.

The power supply to the device is also used for the

DAC voltage reference internally if the internal VDD is

selected as the resistor ladder’s reference voltage.

The typical application requires a bypass capacitor in

order to filter high-frequency noise, which can be

induced onto the power supply's traces. The bypass

capacitor helps to minimize the effect of these noise

sources on signal integrity.

Any noise induced on the VDD line can affect the DAC

performance. Typical applications require a bypass

capacitor in order to filter out high-frequency noise on

the VDD line. The noise can be induced onto the power

supply’s traces or as a result of changes on the DAC out-

put. The bypass capacitor helps to minimize the effect of

these noise sources on signal integrity. Figure 8-1

shows an example of using two bypass capacitors (a

10 µF tantalum capacitor and a 0.1 µF ceramic capaci-

tor) in parallel on the VDD line. These capacitors should

be placed as close to the VDD pin as possible (within

4 mm). If the application circuit has separate digital and

analog power supplies, the VDD and VSS pins of the

device should reside on the analog plane.

FIGURE 8-1:

Example Circuit.

Analog

VDD

SCK

SDO

VSS

VOUT0

To MCU

C1:

0.1 µF capacitor

= Ceramic

C2:

10 µF capacitor

= Tantalum

C3:

~ 0.1 µF

= Optional to reduce noise

in VOUT pin.

C4:

0.1 µF capacitor

= Ceramic

C5:

10 µF capacitor

= Tantalum

C6:

0.1 µF capacitor

= Ceramic

MCP48CXBX2

Optional

(a) Circuit when VDD is selected as reference.

(Note: VDD is connected to the reference circuit internally.)

(b) Circuit when external reference is used.

Output

VREF

6 LAT/HVC

VOUT1

Analog

VDD

SCK

SDO

VSS

VOUT0

To MCU

MCP48CXBX2

Optional

Output

VREF

6 LAT/HVC

VOUT1

Optional

VREF

VDD

SDI

VDD

SDI

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